Preheat the oven to 400°F (200°C). Put the flour in a bowl and rub in the margarine with your fingertips until the mixture resembles fine breadcrumbs. Stir in the cheese and chives, then add enough cold water to bind to a dough. Wrap in plastic wrap and chill, while you make the filling.
Heat the stock in a large pot until boiling, then add the broccoli, leek, beans and peas. Bring back to a boil, cover and simmer for 5 minutes. Drain, reserving 1 1⁄4 cups of the stock.
Divide all the vegetables among four 1 1⁄2 cup pie dishes. Mix the cornstarch with the water and stir in the reserved stock. Pour into the pot and stir over a medium heat until thick and smooth. Add the parsley. Pour over the vegetables.
Roll out the pastry and cover the pie dishes, sealing the rims with a little water. Cut a small vent in each pastry lid. Place on a baking tray and bake for 20-25 minutes until the pastry is firm and golden brown. Serve hot.
Variations: Use any selection of fresh, seasonal vegetables. Tomatoes add a splash of colour, but you could use corn or diced red pepper instead. For meat-eaters, add 4-6 diced strips of lean bacon to the vegetable filling.
Per serving: 409 calories, 18 g fat (4.5 g saturated), 15 g protein, 42 g carbohydrate, 9 g fibre